Filter and absorbing dyes for photographic emulsions



April 5, 19 5 E. BOCKLY ETAL 3,177,078

FILTER AND ABSORBING DYES FOR PHOTOGRAPHIC EMULSIONS Filed Jan. 21, 1963 INVENTORS 5 ER/CH BOcKLY, KARL LGFFLER, RE/NHARD MULLER.

ifik /ATTORNEYS methylation of aminoanthraquinone derivatives.

dyestuifs can be washed out of photographic gelatine lay- United States Patent 3,177,078 FILTER AND ABSORBENG DYES FUR Plifilfi- GRAPHIC EMULSIUNS Erich Biickly, Cologne-Stammheim, Germany, Karl Liimer, deceased, late of Leverhusen, Germany, by Beate Liifler, legal representative, Leverkusen, Germany, and Reinhard Miiller, Leverlrnsen, Germany, assignors to Agfa Alrtiengeseilschaft, Leverlrusen, Germany, a corporation of Germany Filed Ian. 21, 1963, Eser. No. 253,093 Claims priority, application Germany, Feb. 3, 1962, A 39,366 6 Claims. (Cl. 95-74) This invention relates to photographic silver halide emulsions containing light-absorbing additives and photographic elements comprising layers of such emulsions.

The sharpness and resolution of photographic images produce with photosensitive layers of silver halide emulsions are impaired by the light scattering caused by the silver halide grains. This elfect can be reduced by colouring the photosensitive layers with dyestuffs which absorb light in the spectral range to which the emulsion is sensitive, which dyestufis may then be removed after exposure. The harmful effect of the scattered light is attenuated owing to the longer path which the light has to traverse than the light which falls directly on the silver halide granules to produce the image.

The increased sharpness of definition that can be obtained with these absorbing dyestuffs is inevitably associated with a reduction in the photographic sensitivity.

Dyestuffs which still further reduce the sensitivity of the emulsion layers by virtue of their desensitising properties are of course unsuitable.

Dyestuffs, particularly when used for colour photography, must be practically completely decolorised or removed subsequently because even a faint stain of residual dyestuif can considerably impair the quality of a colour image. Many dyestuffs which are decolorised by the agents used in the processing baths, e.g., by sodium sulphite or potassium ferricyanide are useless because mostly the decolorisation is incomplete. It is therefore advantageous to use dyestuffs which can be washed out of gelatine layers.

Dyestuffs which are suitable for absorbing the scattered light particularly in the red sensitive layer of multiple layer photographic materials without having a desensitising action and which may be removed quantitatively from gelatine layers by washing with water are by far rarer than absorbing dyestuffs for the layers which are sensitive' to green or blue.

In French patent specification 1,163,100, dyestuffs are proposed as additives which are prepared by sulpho- The ers. However, these protective dyestufls do not adequately absorb in the 680 to 710 m region which is particularly important in multi-layer colour copying materials because the red sensitive layers have the highest sensitivity in this region.

It is among the objects of-the present invention to provide for the red sensitive layer dyestufis which are easily soluble in water, particularly for colour photographic multi-layer copying materials which have a strong absorp- 'tive action in the whole red region of therspectrum, especially in the region of maximum red sensitivity, which.

have practically no desensitising etfect on the silver halide emulsion and which can readily be washed out with water in the usual course of processing without requiring any additional baths and without leaving any residual'stain.

We have now found-that a particular group of dyestuffs can advantageously be employed in red sensitive fire silver halide emulsions. These blue-green dyestutfs are produced by the action of ferric chloride on sulphonic acids of 1,2-naphthylene diamine. The resulting iron complex dyestuffs, the chemical constitution of which is not completely known in every case, are readily watersoluble and compatible with gelatine-silver halide emulsions and are distinguished by a very wide absorption range which includes the entire red spectrum.

In the region of 620 to 750 mp the absorption of these dyestuffs does not fall below of the maximum absorption of about 710 m The dyestuffs are stable even at very acid or alkaline pH values. Strong reducing agents destroy the iron complexes and causes decolorisation.

The absorbing dyestuffs according to the invention are added in aqueous solution, preferably in quantities of 0.5 to 5 grams per gram atom of silver in the form of silver halide to the gelatine-silver halide emulsions before casting. Based on the quantity of silver halide in the emulsion, we have found that for about 0.5 to about 10 g. of dye per gram mole of silver can be employed, although higher or smaller amounts of dye can be used depending upon particular conditions.- Owing to the high watersolubility of the dyestuifs and their low aflinity to gelatines they become distributed over adjacent layers so that it may be advantageous to colour not only the red sensitive emulsion layer but also the other emulsion layers before casting. The dyestuffs, which are uniformly distributed in all the layers, in addition reduce the intensity of reflected light.

The preparation and application of the dyestufis (A, B, C) according to the invention is described in the following examples and the absorption curves of the dyestuffs are shown in FIGURE 1. For comparison, FIGURE 2 shows the spectral distribution of red-sensitivity of the photographic layer sensitised with dyestuff Rr 1953 (Fiat Final Report No. 943), with themain maximum of red sensitisation in the region between 680 and 710 III/1., which is characteristic for multi-layer copying materials for colour photography.

. Rr 1953 conforms to the following formula:

Example 1 31.8 g. of 1,2-diaminonaphthalene-3,7-disulphonic acid was dissolved by gently heating it in ml. of water and adding 80 ml. saturated sodium acetate solution. 32.4.g. of ferric chloride dissolved in 100 m1. of water were then gradually added with stirring at'30 C. to the yellow solution. After allowing the mixture to stand at room temperature for one hour, the" precipitated dyestulf (A) was isolated by suction filtering and digested twice with a small quantity of 1 5% hydrochloric acid and then filtered by suction until dry in air and subsequently completely dried at 70. 12 g. of dark green powder readily soluble in water to give a clear'solution with a brilliant blue-green colour were obtained.

A solution of 0.6 g. of this dyesauff in 30 ml. Water was added to 1 kg. of a gelatine-silver chlorob-romide emulsion which had been sensitised to red with dyestuil' R1 1953 (Fiat Final Report No. 943) and which also contained 15 g. of the blue green coupling agent l-oxy- 2-naplrthoyl-4-sulphooctadecylamide, the solution of the dyestutf being added in the proportion 3.7 g. dyestuil per gram atom silver.

This emulsion was used for the middle layer of a three.

layer positive colour film. The lowest layer applied on a cellulose triacetate foil consisted of a blue sensitive gelatine-si-lver bromide emulsion with yellow colour coupler, andthe uppermost layer was a green sensitive gela-.

tine-silver chlorobromide emulsion with magenta colour coupler. The layers contained about 42 mg. of dyestufi (A) per mP. film was composed without the addition of absorbing dyestuff.

'Samples ofthe two film materials were treated for 8 minutes in a colour developer bath of the following composition;

scribed, for example, on page 953 of the Merck Index, 7th Edition.

For comparison, the same three layer When the material had been bleached and fixed by the usual methods, no stain was detected in the two materials but the sharpness of the'image in the material that contained the absorbing dyestuif according to the invention was much better.

Example 2 50 g. of 1,Z-diaminonaphthalene-S,7-disulphoni-c acid was dissolved by heatingin 350 ml. of water and 49 g. potassium acetate were added. 170 cc. of a 3 1% ferric chloride solution were stirred at into this intensely coloured yellow solution. After stirring for one hour at room temperature, the precipitated dyestuff (B) was filtered off by suction, pu-rifiedby digesting with 20%.

hydrochloric acid and dried at 70. 27 g. of a dark green powder, soluble in water to give a brilliant bluegreen solution were obtained.

A three layer positive colour-film was built up as in Example 1, except that all the layers contained 0.6 g.

of dyestulf (B) per kg. of emulsion, corresponding to. V A micro line screen was illuminated on to samplesof this film and about 120 mg.,per m? of film surface.

on to another film used for comparison which was made in the same way but without the addition of protective dyestulf (B). After developing the colour as in Example ;l,' the following fog densities were measuredforthe .unilluminated areas:

Bluc- Magenta Yellow green warmer absorbing dyestufi (B) o. 07 0.08 0.11 With absorbing dyestufl (B) 0. 07 0. 09 0.10

I On projecting the films and on microscopic interpretation ofthe screen images, the material without absorbing dyestufi gave a resolution of 140 lines/mm. whereas the V Example 3 V 35.4 g; l,Z-diaminonaphthalene-f;,6-disulphonio. acid used such as cyanmes, 'merocyanines, complex (trinuclear) and 29.4 g. potassium acetate were dissolved together in 200 ml. water. 32 g. of ferric chloride dissolved in 100 ml. water were added at 35 with stirring. The product was filtered after 15 'minutes and the filtrate was treated with 1 /2 times its volume of alcohol and the precipitated dyestufi (C) was separated by suction filtration, washed with about 50 ml. of 96% alcoholand dried in a drying oven at 70. 37v g. of a greenishblack powder readily soluble in water to give a clearblue green solution were'obtained.

0.5 g. of this dyestufi was dissolved in'25 ml. water and added to 1 kg. of agelatine-silver chloride emulsion which had been sensitised to red with dyestutl Rr 1953 and which containedv 12 g. of the blue-green coupler 1- hydroxy- 2 naphthoyl 4 sulphooctadecylamide. This emulsion was cast as the uppermost layer over a layer consisting of a blue sensitive gelatinersilver bromide, layer with yellow colour couplers on papercoated with barium.

2 g. Calgon 1 2 g. hydroxylamine sulphate 4 g. sodium sulphite 1 g. potassium bromide 1 1. water I 100 g. potassium carbonate V 5 g. -N,N-dibutyl-p-phenylendiamine w-sulphonic acid A sodium hexametaphosphatecontaining detergent as desjc ged, for example, on page 953 ofthe Merck Index, 7th

1 ion.

After bleaching. and fixing .thesamples in. the usual-way the following difierences in 'fog density hardly perceptible with the naked eye werermeasured:

nwiu be. clear to thoseskilled: .intheartthat the praXis of our-invention lends'i-tselt readily to a number of usefulmodifications in method, materials and so on; The photographic. silver halideemulsions can be optically sensitised or unsensitised- The usual optical sensitising dyes for' the red range of the. visible spectrumcanbe cyanines or merocyanines,.. styryls etc. vIn generahthe particular dyes according .to therinvention should have its maximumabsorption-in the samespectralrregion to" which theQsensitising dye sensitises the emulsion.

' The dyestuffs-can be :usedfor silver chloride, bromide, or iodide emulsions, or for emulsions-containing mixtures of'silver-halidesa. Emulsions ofsilver chloride'orsilver chloro bromide are. preferred. While our inventionis particularly directed to .the ordinary employed silver halide gelatine emulsions, binding agents other than .gelatine, e.g.',' polyvinyl alcohol or. cellulose materials; .such 1 as hydrolyzed cellulose acetate; carboxymethyl. cellulose I or the like which haveno; deleterious etlect upon the lightsensitive materials, can beemployed aloneor in comb1nation.with.gelatine;. i g

The emulsions prepared in accordance with our inven- 'tion can. be coated in the usual manner uponany suitable material with absorbing dyestuft had a resolution of p I lines/mm. and much better contrast.

support, ,elg... cellulose acetate. films, polycarbonate ifilms, polystyrene films,:polyester filmsetc. V

We have found that the advantages of our invention are particularly outstanding when the support is paper or some other fibrous material which is more likely'to adsorb stain. than hydrophobic materials; I

The silver halide emulsions according. to the invention etc.

can also contain such addenda as chemical sensitisers, e.g., sulpho sensitizers, various gold compounds, palladium compounds and the like; antifoggants, hardeners The blue-green colour-coupler used in the emulsion according to the invention is not especially critical and is selected according to the requirements of the particular copying material in which the emulsion is to be used.

We claim:

1. A photographic silver halide gelatine emulsion optically sensitised to the red region of the spectrum containing from about 0.5 to 10 g. per mole of silver halide of a water soluble dye, said dye being a reaction product of ferric chloride with 1,2-diaminonaphthalene disulphonic acids, said reaction product having its maximum absorption in the red region of the spectrum.

2. A photographic silver halide gelatine emulsion according to claim 1, containing from about 0.5 to 10 g. per mole of silver halide, of the reaction product of ferric chloride with 1,2 diaminonaphthalene 3,7 disulphonic acid.

3. A photographic silver halide gelatine emulsion according to claim 1, containing from about 0.5 to 10 g. per mole of silver halide, of the reaction product of ferric chloride with 1,2 diaminonaphthalene 5,7 disulphonic acid.

4. A photographic silver halide gelatine emulsion according to claim 1, containing from about 0.5 to 10 g. per mole of silver halide, of the reaction product of ferric chloride with 1,2 diaminonaphthalene 3,6 disulphonic acid.

5. A photographic element for subtractive colour photography comprising a support having coated thereon a plurality of silver halide emulsion layers, one of which is sensitive to the blue region of the spectrum and contains a colour-forming compound capable of coupling with the oxidation products of a colour developer to produce a yellow image, one of which is sensitive to the green region of the spectrum and contains a colour-forming compound capable of coupling with the oxidation products of a colour developer to produce a magenta image and one of which is sensitive to the red region of the spectrum and contains (1) a colour-forming compound capable of coupling with the oxidation products of a colour developer to produce a cyan image and 2) from about 0.5 to 10- grams per mole of silver halide of a water soluble dye having its maximum absorption in the red-light region of the spectrum, said dye being a reaction product of ferric chloride with 1,2-diamiuonaphthalene-disulphonic acid.

6. A photographic element according to claim 5, wherein the support is paper and a silver halide emulsion layer closest to the support is a blue silver halide emulsion layer, the silver halide emulsion layer farthest from the paper support is a red sensitised silver halide emulsion layer and the green silver halide emulsion layer lies between the red sensitised silver halide emulsion layer and the blue sensitive silver halide emulsion layer.

References Cited by the Examiner FOREIGN PATENTS 1,163,100 9/58 France.

OTHER REFERENCES Sommer: Chemicke Lisy, vol. 52, pages 1485-1500 (1958).

NORMAN G. TORCHIN, Primary Examiner. 

5. A PHOTOGRAPHIC ELEMENT FOR SUBTRACTIVE COLOUR PHOTOGRAPHY COMPRISING A SUPPORT HAVING COATED THEREON A PLURALITY OF SILVER HALIDE EMULSION LAYERS, ONE OF WHICH IS SENSITIVE TO THE BLUE REGION OF THE SPECTRUM AND CONTAINS A COLOUR-FORMING COMPOUND CAPABLE OF COUPLING WITH THE OXIDATION PRODUCTS OF A COLOUR DEVELOPER TO PRODUCE A YELLOW IMAGE, ONE OF WHICH IS SENSITIVE TO THE GREEN REGION OF THE SPECTRUM AND CONTAINS A COLOUR-FORMING COMPOUND CAPABLE OF COUPLING WITH THE OXIDATION PRODUCTS OF A COLOUR DEVELOPER TO PRODUCE A MAGENTA IMAGE AND ONE OF WHICH IS SENSITIVE TO THE RED REGION OF THE SPECTRUM AND CONTAINS (1) A COLOUR-FORMING COMPOUND CAPABLE OF COUPLING WITH THE OXIDATION PRODUCTS OF A COLOUR DEVELOPER TO PRODUCE A CYAN IMAGE AND (2) FROM ABOUT 0.5 TO 10 GRAMS PER MOLE OF SILVER HALIDE OF A WATER SOLUBLE DYE HAVING ITS MAXIMUM ABSORPTION IN THE RED-LIGHT REGION OF THE SPECTRUM, SAID DYE BEING A REACTION PRODUCT OF FERRIC CHLORIDE WITH 1,2-DIAMINONAPHTHALENE-DISULPHONIC ACID. 